Image Sharing with Steganography and Authentication - Visual Cryptography and Secret Image Sharing - page 440

FIGURE 16.20
The four pixels of each cover block CBi.

Step 4: To prevent illicit attempts, a simple authentication ability is

added here. Compute check bits pi by using Equation 16.17 and
embed pi into the remaining LSBs of Ci, i , D i , G i , H i from the
same cover block CBi, i , where i = 1, 2, ..., t. Note that t is the
total number of check bits, which is discretionary and could be
decided by the sender according to authentication strength. For
simplicity, we take t = 2 as an example to explain the procedure
as shown in Figure 16.22. Figure 16.23 illustrates a flowchart of

FIGURE 16.21
Hiding the six data bits of F(Xi).